Incandescent ignition device



Filed July 25, .1930 I5 Sheets-Sheet l INVENTOR IRA E. W cm BY ATTORNEY iqi Dec. 1, 1931. 1. E. M CABE' INCANDESCENT IGNITION DEVICE Filed July 25, 1950 3 Sheets-Sheet 2 'I 22 'fi- 3 5 INVENTOR 2 {RA ELI/W CASE BYAO ATTORNEYYM Dec. 1, 1931. r l. E. McCABE 1,83 89 INCANDESCENT IGNITION DEVICE Filed July 25 1930 3 Sheets-Sheet 3 INVENTOR IRA E... W CABE ATTORNEY Patented Dec. .1, 1931 PATENT? OFFICE m E. McGAIBE, or cnroneo, ILLINOIS IGNITION DEVICE Application filed July 25,

This invention relates to improvements in incandescent ignition devices for electrically operated and controlled forced draft domestic fluid fuel burning mechanisms and more 6 particularly to means for maintaining the ignition device incandescent when subjected to the cooling influence of the forceddraft passing thereover.

In fluid fuel. burners employing the so- 10 called hot wire ignition device, it is common practice to provide a preheating time by passing the ignition circuit'through the device to bring it to incandescency before the motor circuit is closed to supply the fluid fuel which in passin over or about the incandescent igniter is ignited thereby. It is obvious that the ignited must be adjacent the fluid fuel as it is supplied by the burner mechanism. It is also common practice to employ an ignition circuit of only suificientcurrent to heat the ignition device in passing therethrough to incandescency.

In fluid fuel burning mechanism of the forced draft type, it is common practiceto cause the motor which supplies the fuel to the ignition 'device to also at the same time supply air under pressure to mix with the ignited fuel to insure more complete combustion. This forced draft is not only initiated as the fuels'upply is initiated but also passes over the ignition device, so that a hot wire type of ignition device that has been heated to incandescency is subjected to the cooling effect of the forced draft passing thereover. It has been found that in'certain commer cial fluid fuel burner mechanisms of the forced draft type that a hot wire ignition device that has been reheated by the passage of a currentof su cient voltage to make it o incandescent during the preheating period, will be reduced intemperature by the forced draft to such an extent it will not remain hot enough to i ite the fluid fuel. .It has also been found t at if the current of the ignition;

circuit is increased sufliciently to maintain the ignition device incandescentunder the cooling influence of certain forced drafts such current passing through the igmter during the preheating period, before the forced draft is initiated, is so great that it will cause 1930. Serial No. 470,556.

the ignition device to deteriorate, disintegrate, be consumed and become inoperative. The object of this invention is to provide means that will automatically control the current of the ignition circuit so that when it..is

desired to operate the burner mechanism the current will be of such strength to bring the ignition device to incandescency without harm to it during the preheating periodand then as the fuel and additional air under pres- 00 sure are passed over the device the current is at the same time increased sufliciently to maintain the device incandescent/to insure ignition of the fuel.

With-these and other objects in view referonce 18 made to the accompanyingsheets of drawings, which illustrate preferred forms of this invention, with the understanding that minor detailchanges may be made without departing from the scope thereof. In the drawings:

-Figure 1- is a view of a control unit, in front elevation with the cover removed, illustrating an embodiment of this invention.

' Figure 2 is a diagrammatical view illustrating an installation of a fluid fuel burner in connection with a domestic heater installed with the control illustrated in Figure 1, and showing a wiring diagram of the electrical connections and controls employed with the so burner mechanism illustrated.

Figure 3 is a view in horizontal central section of a draft pipeof a fluid fuel burner mechanism, illustrating the burner assembly in top plan view and illustrating a modified form of this invention.

Figure 4 is a view in transverse vertical sectlon taken on the line-4,4 of Figure 3 looking in the direction of the arrows.

Figure 5 is'a detail view in front elevation of the'switch carrier plate employed-in Figures 3a I e As a e stated, this invention relates to means whereby an incandescent i iter employed in connection with a force draft or as gun'type domestic fluid fuel burner may be brought to incandescence before the forced draft passes thereover and maintained at incandescency while the forced draft is passed thereover, without detriment to or deteriora- Figure 1 illustrates a commercial type of constant current transformer actuated control adapted to be installed in the control system of an electrically operated fluid fuel burner mechanism, such as disclosed in the applicants rior copending application, Se-

rial #446,5 3, filedApril 23, 1930, which embodies the improvements carried out in the further development of this articular control, as illustrated in the apphcants. copending application Serial #465,882pfiled July 7, 1930. This particular control is illustrated in the diagrammatical view in Figure;

. 2 as connected in the control system. Referring to Figure 2, a fluid fuel burner mechanism 1 of commercial type is shown installed in connection with a domestic heater 2 of commercial type. The burner mechanism 1 is diagrammaticallyillustrated as being .of the forced draft or gun type which is well recognized in this art and, therefore, it is not thought necessary to describe the construction and ope 'ation of this mechanism,

othertha'n the statement that it is operated by an electric motor 3, which motor creates I a forced draft through the draft pipe 4 and at the same time supplies fluid fuel through a fuel pipe 5 arranged centrally within the draft pipe to discharge the fluid fuel through a nozzle arranged within the open end of the draft pipe within the domestic heater. In burners of this type, the ignition devices are custbmarily mounted upon the fuel pipe and the fuel pipe nozzle and ignition device is termed the burner assembly. The ignition device shown in Figure 2 comprisesan incandescent igniter 6 such as disclosed in the applicants prior copending applications Serial No. 331,542, filed January 10, 1930, and Serial No. 441,143, filed April 2, 1930.

The control device, illustrated in detail in Figure 1, is mountedupon panel 7 and incl ldes a motor switch 8 normally opened and ignition switch 9 normally closed, a hold- 4 l6 ondary coil resting upon the lower interior @on the panel 7 ythe wire S through said ing magnet 10 normally ,deenergized, and also side thereof and the primary coil adapted to float thereabove. I

Referring to the wiring diagram in Figure 2, it is seen that the commercial current enters through a wire 14 passes through a commercial boiler control B, normally closed,

- and from thence through a commercial room thremostat T to a binding post upon the control panel 7 andyafter passing through the various switches and coils on the control panel, the commercial current returns froin another binding post upon the panel 7 through the wire 15 to the commercial line.

As disclosed-in said prior copending applications Serial N 0. 446,573, filed April 23, 1930, and No. 465,882 filed July 7, 1930, when the room thermostat calls for heat, by closing the circuit to the control panel, the commercial current passes first through the normally closed ignition switch 9, the primary coil 11 of the constant current transformer, and back to the commercial line,thereby energizing the secondary coil 12 of the constant current transformer. This coil 12 is connected by wire 16 to convey the secondary current/through theincandescent igniting element 6 and back to the other terminal of said coil. As disclosed in said prior copending applications Serial No. 446,573, filed April 23, 1930, and No. 465,882, filed July 7, 1930, the energizing of the secondary coil 12 of the constant current transformer sets certain mechanism on the control panel into operation to first close the motor switch 8 and then open the ignitionswitch 9, whereby the commercial current from line 14 thereafter passes through said motor switch 8 and burner motor 3 back to the panel binding post connected with the return lead 15 to the commercial source of electricity. 'The starting of the motor initiates the draft thereafter forced through the draft pipe 4 and at the same time delivers fluid fuel through the nozzle adja'- cent the ignition device 6. As described in said prior copending application, the heat generated within the domestic heater 2 bythe lgnition of the fluid fue'lacts upon a normally open combustlon responsive switch S, causing same to close whereby the incoming commercial current asses from the binding post switch and from thence through the coils of holding magnet 10 to the binding post of the return lead to the commercial source of electr1c1t whereby the niotor. switch islocked in close position and the ignition switch is held 1n open position, so. that after the ignition of the fluid fuel the secondary current passing through the igniter elemen 6 is discontinued. The above is a descrip ion of a commercral control system for a fluid burner and the normal operation in starting the mechanism has been described. This invention contemplates the addition tothe ignition circuit ofan incandescent igniter of means whereby the pipe and over the ignition element. As shown includes a normally closed switch 21 which in Figures 1 and 2 a resistance element 17 is placed in the ignition circuit of the incandescent igniter and is preferably contained within the casing 18 mounted upon the top of the control panel 7 and, if desirable, is provided with a fuse orcut-out 19, as shown.

This resistance element is connected by wire. 20 in parallel with the wires 16 of the sec-- ondary circuit which, when energized, passes through the 'lgnlter 6. -Th1s resistance c1rcu1t is shown in Figural of the drawing as being mounted upon the same support as the nor,- mally open motor switch 8 so that when the motor switch 8 is closed the resistance switch 21 will be opened.

As heretofore stated, this invention forms a part of the ignition system of .an incandes cent ignition device employed in a forced draft or gun type of fluid fuel burner, in which the igniter must necessarily be adjacent the discharge of the fuel pipe and, therefore, subjected to the cooling influence of the forced draft passing thereover while the fuel is ignited and during-combustion. Under normal conditions, ordinarily the current of the secondary current is only sufficient to preheat or bring the igniter member to incandescency prior to the operation of the motor and will not be suflicient to continue the igniter in an incandescent condition during the passage of the forced draft thereover. If the current of the ignition device was of sufficient strength to maintain the igniter in an incandescent state after the forced draft began passlng thereover, it would be .of suflicient strength during the preheating stage prior to the pas-.

sage of the forced draft to cause the igniting member to deteriorate or be consumed. Different types of forced draft burners employ different mtensities of drafts so that the cooling eflect u on a normally incandescent igniter woul Vary. It is, therefore, desirable to adjust the resistance 17 so that when the room thermostat calls forheat the secondary circuit set up through the wires 16, in which the normally closed resistance switch 21 and resistance element 17 are connected in parallel through the wires 20, will be such that the i iter 6 through the preheating period will ecome incandescent and when the 'motor switch 8 is closed and the resistance switch 21 opened thefull strength of the current in the secondary circuit passing through the igniterwill then beqsuflicient to maintain the igniter in an incandescent state until igniticular control illustrated in Figure 1. Some.

types of forced draft domestic fluid fuel which is swung about a horizontal axis by the passage of the forced draft through the draft pipe. Another embodiment of thisinvention is illustrated in Figures 3, 4 and 5 which illustrate its application to this type ofdamper equipped forced draft burner mechanism. Figures 3 and 4 illustrate a damper 22 within the draft pipe 4 mounted to swing upon the horizontal pivot shaft 23, mounted in bearings secured to the interior of the draft pipe 4. One end of the pivot shaft 23 extends through a side of the draft pipe and carries upon its exterior end a switch carrier plate 24 upon which the resistance switch 21 is mounted. The exterior of the draft pipe is preferably provided with stops 25 so arranged that when the motor is idle and the damper normally assumes a vertical position, the switch carrier plate 24 will contact one of the stops and will mount the resistance switch 21 in closed position. As soon as the motor starts and the forced draft passes through draft pipe 4 the damper 22 will beswung about its pivot by the impetus of the-air passing through the draft pipe and carried to a horizontal position and maintained in that position during the operation of the motor. As the damper 22 swings into the horizontal position the carrier plate 24 will rotate the ignition switch 21 and swing it into open positlon, as illustrated in dotted lines on Figure 5. It is preferable to arrange the other stop 25 to engage the carrier plate24 to prevent a further rotation of the ignition switch 21..

In this form it is preferable to provide a cover 26 about the carrier plate and resistance switch, which may be secured to the side of ignition circuit, an igniter in said circuit.

adapted to be brought to incandescence by the passage of the current of the ignition circuit therethrough, and means to vary the-currentof the ignition circuit to maintain a current suflicient to bring the igniter to incandescence during the preheating cried and increase the current during the active ignition period.

2. An i n'tion device for an electrically operated u1d fuel burner mechanism of the forced draft type including a constant currenttransformer in the ignition circuit, an igniter in circuit with the constant current side of the transformer and in the path of the forced draft, and means for sup lying a current in the ignition circuit sufliclent to bring the igniter to incandescefice prior to the initiation of the forced draft, and increase the strength of said current after the initiation of said forced draft.

3. A hot wire ignition device for an electrically actuated forced draft fluid fuel burner mechanism including a constant current transformer in the ignition circuit, an igniter in circuit with the constant current side of the transformer and in the path of the forced draft, and means for supplying a current sufiicient to bring the igniter to incan descence prior to the starting of the burner motor and for increasing the said current sufficiently to maintain the igniter incandescent during the passage of the forced draft there over.

4. Ahot wire ignition device for an electrically actuated forced draft fluid fuel burner mechanism including a constant current transformer in the ignition circuit, an igniter in circuit with the constant current side of the transformer in the path of the forced draft, and means included in the ignition circuit for supplying a current sufiicient to bring the igniter to incandescency prior to the initiation of the forced draft, and for increasing the saidrcurrent sufiiciently to burner mechanism including a constant current transformer in the ignition circuit, an igniter in circuit with the constant current side of;the transformer in the path of the forced draft, means included in the ignition circuit for supplyinga current sufficient to bring the igniter to incandescency prior to the initiation of the forced draft, and means actuated by the initiation of operation of the.

burner motor for increasing the said current sufiiciently to maintain the igniter incandescentduring the passage of the forced draft thereov er. I

6. A hot wire ignition device for an electrically actuated forced draft fluid fuel burner mechanism including a constant current transformer in the ignition circuit, an

igniter in circuit with the constant current side of the transformer inthe path 'of the forced draft, means, including a resistance normally in the ignition circuit for supplying a current sufiicient to bring the igniter to incandescency prior to the initiation of the forced draft, and means for cutting out said reslstance for increasing the said current sufficiently to maintain the igniter incandescent during the passage of the forced draft thereover.

7. A hot wire ignition device for an electrically -actuated forced draft fluid ,fuel burner mechanism including a constant current transformer in the ignition circuit, an igniter in circuit with the constant current side of the transformer and in the path of the forced draft, means, including a resistance element normally connected in parallel in the i nition circuit for supplying a current sufficient to bring the igniter to incandescency prior to the initiation of the forced draft, and means for opening the resistance circuit for increasing the said current sufficiently to maintain the igniter incandescent during the passage of the forced draft thereover.

8.v A hot wire ignition device for an electrically actuated fluid fuel burner mechanism including a constant current transformer in the ignition circuit, an igniter in circuit with the constant current side of the transformer and in the path of the forced draft, means, including a resistance element normally connected in parallel in the ignition circuit and a normally closed switch in the resistance circuit for supplying a current suflicient to bring the i gniter to incandescency ,prior to the initiation of the forced draft, and means actuated by the initiation of operation of the burner motor to open the resistance switch for increasing the said current sufficiently to maintain theigniter incandescent during the passage of the forced draft thereover.

candescency prion to the supplying of fuel and air under pressure and automatically increasing the strength of the ignition current initiated at the same time with the supply of fuel and air under pressure to maintain the ignition device incandescent and compensate for the cooling effect of the forced draft passing thereover.

, IRA E. McCABE. 

